Means for controlling the charge of storage batteries



F. G. BEETEM Nov. 24, 1931.

MEANS FOR CONTROLLING THE CHARGE OF STORAGE BATTERIES Filed July 25, 1950 //VVE/V70/? Han 1; .5 Cc? 2. 6/7? Wm 55: pflmz By W jfroewex Patented Nov. 24, '1931 UNITED STATES PATENT OFFICE" FRANK G. BEETEM, OI PENNSYLVANIA MEANS FOR CONTROLLING THE CHARGE OF STORAGE BATTERIES Application filed July .25,

My invention applies to systems in which a storage battery is charged from a suitable generator at either of two charging rates, depending upon the batter voltage, the charging rate being reduced rom the higher rate to the lower rate at a certain predetermined battery voltage. My invention is especially applicable to systems in which a charging generator is connected to the storage battery by means of an automatic swltch or cut-out designed to close when the generator voltage reaches a certain value and to open again when the generator voltage drops to some lower value.

An object of my invention is to provlde a voltage, responsive relay adapted to reduce the charging rate from the higher value to the lower value and to rovide means whereby the exciting coil 0 this relay is disconnected until after the generator is connected to the battery b means of the automatic switch. Other 0 jects of the invention are to provide apparatus for carrying out the desired objects which shall be simple in construction, inexpensive to manufacture and reliable in operation. M invention Wlll be more clearly understood y reference to the accompanying drawing in which is shown diagrammatically a system disclosing one embodiment of my invention applied to a combination of battery and charging generator, the latter of the third brush type such as is generally employed for startlng and lighting s stems on automobiles.

In the rawing, 1 is a charging generator of the third brush type connected to the circuit 2, 3, its field coil being shown at 21. This field coil is connected between the third brush of the machine and the conductor 3 through a fixed resistor 20. The resistor 20 is normally short circuited through the contacts 18 of the voltage responsive relay R, which is provided with a magnetic core 15 and an armature 17 pivoted at 22. The core 15 is provided with an exciting coil 16 connected across the circuit 2, 3 through the con- I tacts 9 of the relay A. The contact 18 mounted on the armature 17 makes contact with a bimetallic strip 19 so arran ed that at higher temperatures the free en of this bimetallic strip rises, moving the armature 17 nearer to the core 15, thus reducing the air gap and causing the armature to be attracted into its upper position to break the contact 18 at a lower voltage than that required when the temperature is low.

The closing of the contacts 9 of the relay A is determined by the combined action of the voltage coil 4 connected directly across the circuit 2, 3, and the series coil 5 which carries the current delivered from the generator to the battery when the contacts 10 .of the automatic switch B are closed.

The automatic switch B is of the well known type, having a core 14, a shunt coil 6 55 and a series coil 7. The shunt coil 6 is connected across the circuit 2, 3, and when the generator reaches the voltage for which the automatic switch or cut-out B is adjusted, the excitation of the coil 6 is sufiicient to lift the armature 12 against the force exerted by spring S and close the contacts at 10, connecting the generator 1 to the battery 8 Referring again to the relay A, the adjustment of the relay A and the automatic switch B is such that the excitation of the coil 6 on the switch B will always close the contacts 10 before the excitation of the coil 4 on the relay A is sufiicient to close the contacts 9. After the contacts 10 are closed, current will flow from the generator 1 to the battery 8 through the series coil 5 of relay A, and the excitation of this coil added to that of coil 4 will be sufiicient to close the contacts 9, thus completing the circuit of the exciting coil 16 of relay B. At the beginning of the charging period, the voltage across the circuit 2, 3 will not be sufficient to cause the relay R to lift the armature 17 and open the contacts at 18. As the battery becomes more 'fully 1980. Serial No. 470,696.

assure charged, the volta will rise until at a certain predetermine voltage the contacts 18 will be opened and the charging rate reduced by the insertion of the resistance 20 in series with the field coil 21.

The object of the arrangement shown in this drawing may be explained as follows:

It is desirable to connect the coil 16 on the generator side of the automatic switch B so that when the generator is not in operation and the automatic switch is open, the coil 16 will be disconnected from the battery and will not constitute a continuous drain of current from the battery when the generator is idle. However, when the coil 16 is connected across the generator, the generator voltage may rise to an excessive value sufiicient to attract the armature 17 and open the contacts at 18 before the automatic switch B is closed. This will start the chargin of the battery at the low rate instead of the 'gh rate whereas it is always desirable to start the charge at the higher rate. In order to avoid this diflicult the relay A has been introduced and so esi ed that the circuit of the coil 16 cannot e closed until after the automatic switch B has closed. As soon as the automatic switch B closes, the'voltage of the generator will drop to that of the battery, and as explained above, this voltage will not be sufficient to actuate the relay R until the batteziy charge has been nearly completed.

t will e noted that the relays A and B are similar in construction and performance and in fact they may be identica in design except for a slight diflerence in adjustment to insure that the switch B will close before the switch A. By making these two switches identical, the cost of roduction is materially reduced.

Having escribed one embodiment of my invention, what I claim and desire to secure by Letters Patent is:

1. In combination, a storage batter a generator and its circuit including a v0 tage responsive exciting coil adapted to be connected across said generator for adjusting the charging rate to the battery selectively at either a higher or a lowervalue, an automatic switch for connecting the source to the battery, a relay adapted to control the adjusting means, said relay having a voltage responsive exciting coil, and means for connecti said coil to the circuit between the source an the automatic switch only after said automatic switch has closed.

2. A charging apparatus for batteries includin in combination, a third brush erator, a attery adapted to be connected to two of the brushes of the generator, a field coil for said generator connected to the third brush of the generator, a fixed resistor connected in series with said field coil between said third brush and one of the other brushes of the generator, a connection in parallel with said resistor containing an armature and a FRANK G. BEETEM. 

